The present invention relates to a method for controlling a vehicle drive electric motor.
In a prior art method for controlling a vehicle drive electric motor, as disclosed by JP-A-6-98419, a motor torque degree order signal is calculated from a vehicle speed and an accelerator operating degree, the motor torque degree order signal is set to zero when a drive stop range for deenergizing a motor is selected, and the motor torque degree order signal is compensated to prevent an abrupt increase of motor output torque when the vehicle drive mode is changed from the drive stop range to a drive range for energizing the motor.
An object of the present invention is to provide a method for controlling a vehicle drive electric motor, preferable for preventing an abrupt acceleration of the vehicle when a vehicle drive mode undesirable for an actual vehicle moving condition is ordered erroneously by a vehicle operator.
According to the present invention, a method for controlling a vehicle drive electric motor whose output torque degree is ordered in accordance with a movement of an accelerator, comprises the steps of:
detecting an actual vehicle moving condition,
judging whether or not the detected actual vehicle moving condition is in compliance with a vehicle drive mode ordered by a vehicle operator,
decreasing an actual output torque of the vehicle drive electric motor when the detected actual vehicle moving condition is not in compliance with the ordered vehicle drive mode, to less than the output torque degree of the vehicle drive electric motor ordered in accordance with the movement of the accelerator, and
thereafter making the actual output torque of the vehicle drive electric motor substantially equal to the output torque degree of the vehicle drive electric motor ordered in accordance with the movement of the accelerator after the detected actual vehicle moving condition becomes in compliance with another vehicle drive mode ordered by the vehicle operator to correct the previously erroneously ordered vehicle drive mode and the output torque degree of the vehicle drive electric motor ordered in accordance with the movement of the accelerator is decreased to not more than the decreased actual output torque of the vehicle drive electric motor.
Since the actual output torque of the vehicle drive electric motor is decreased when the detected actual vehicle moving condition, for example, vehicle proceeding direction or vehicle proceeding speed, is not in compliance with the ordered vehicle drive mode, to a decreased value less than the output torque degree of the vehicle drive electric motor being ordered in accordance with the movement of the accelerator, and is made substantially equal to the output torque degree of the vehicle drive electric motor as being ordered after the detected actual vehicle moving condition becomes in compliance with another vehicle drive mode being ordered by the vehicle operator to cancel or correct the previously erroneously ordered vehicle drive mode and the output torque degree of the vehicle drive electric motor being ordered in accordance with the movement of the accelerator is decreased to not more than the decreased value, the abrupt acceleration of the vehicle caused by the output torque degree of the vehicle drive electric motor ordered in accordance with the movement of the accelerator when the erroneous vehicle drive mode was ordered is prevented by a decrease of the output torque degree of the vehicle drive electric motor, even if, while the vehicle continues to proceed forward, the other vehicle drive mode, D vehicle drive mode for driving forward the vehicle, is ordered by the vehicle operator to cancel or correct the previous erroneously ordered vehicle drive mode, N vehicle drive mode for deenergizing the vehicle drive electric motor, R vehicle drive mode for driving backward the vehicle or P vehicle drive mode for deenergizing and locking the vehicle drive electric motor, or if, while the vehicle continues to proceed backward, the other vehicle drive mode, R vehicle drive mode, is ordered by the vehicle operator to cancel or correct the previous erroneously ordered vehicle drive mode, D vehicle drive mode, N vehicle drive mode, or P vehicle drive mode.
The actual output torque of the vehicle drive electric motor may be made substantially equal to the output torque degree of the vehicle drive electric motor ordered in accordance with the movement of the accelerator, after the detected actual vehicle moving condition becomes in compliance with the ordered vehicle drive mode and the output torque degree of the vehicle drive electric motor being ordered in accordance with the movement of the accelerator is decreased to a predetermined degree generally not more than the decreased value, for example, substantially to zero. The actual output torque of the vehicle drive electric motor may be decreased to a predetermined decreased value generally less than the output torque degree of the vehicle drive electric motor being ordered in accordance with the movement of the accelerator, for example, substantially to zero with deenergizing substantially the vehicle drive electric motor when the detected actual vehicle moving condition is not in compliance with the ordered vehicle drive mode.
An alarm signal for the vehicle operator may be generated when the detected actual vehicle moving condition is not in compliance with the ordered vehicle drive mode, and be cancelled when the detected actual vehicle moving condition becomes in compliance with the ordered vehicle drive mode or when the output torque degree of the vehicle drive electric motor being ordered in accordance with the movement of the accelerator is decreased to not more than the decreased actual output torque of the vehicle drive electric motor. The actual output torque of the vehicle drive electric motor may be decreased while generating electricity from the vehicle drive electric motor to brake the vehicle.